This invention relates to a predictive shock alert warning system comprising sensor probes and an apparatus installed in or near a body of water such as a swimming pool, a river, or a lake. The sensors are placed in the body of water and the apparatus on, or adjacent to, the pool, a swimming dock, or a boat dock in a marina or the like. The system provides an audible and visual alarm when a sensed electrical voltage in the water is of a level approaching that which can seriously shock or electrocute people who may be in the water or about to enter the water.
It is well-known by those living on or near lakes, rivers, and other bodies of water, that a voltage associated with electrical currents or electrical gradients present in a pool or in the water near a shore, a dock, or a boat, etc., can, on occasion, rise to a level by which someone in the water and exposed to the voltage, can be seriously injured or electrocuted. Sadly, there are numerous recorded instances where people, particularly children, have died or been severely shocked when they inadvertently were exposed to a voltage which exceeded the threshold for causing injury or death. The cause of these electrical shock drowning (or ESD) conditions vary widely depending upon a number of factors with a faulty electrical ground or faulty electrical equipment being but two such conditions which can result in a current or voltage gradient near the shore, dock, or boat. Other factors include condition of the water (i.e., its salinity, temperature, if the water is clear or murky, etc.) as well as a person's body weight. Importantly, there is usually no visual indication that water in a swimming pool or in the proximity of a swimming dock, or a boat dock is electrified.
In the July, 2013 edition of Seaworthy magazine, in an article titled: ESD Explained, the author described (at page 7 of the periodical) that ESD arises from three conditions which are a) an electrical fault in which electricity is escaping from somewhere in an electrical system and is trying to find a path back to its source; b) an AC safety ground fault is present by which the AC grounding system has somehow been compromised so stray current cannot return to electrical ground through a ground safety wire; and c) there is no ground fault safety protection. The article goes on to warn about swimming within 100 yards of a marina, boat yard or any dock using electrical power. However, as noted above, despite such possible warnings, people do swim in these areas.
What level of voltage can be dangerous to someone in contact with the water? In the open access journal eplasty (www.eplasty.com) article Conduction of Electrical Current to and Through the Human Body: A Review, by Dr. Raymond Fish, a person stood in buckets filled with fresh water to a level near the person's hip. Testing indicated that with a voltage of 3.05V applied between the plates, there was an involuntary flexion of the person's knees to 90° and this flexion could not be overcome by voluntary effort of the person. With an application of 4.05V, the knee involuntarily flexed to 135°, bringing the person's foot up to near their buttock; and, again this flexion could not be overcome by voluntary effort of the person. It will be appreciated by those skilled in the art that, at a minimum, these situations could greatly affect a person's ability to swim toward a shore or a dock ladder in order to get themselves out of the water.
Also, while obviously not being tested on persons, increasing voltage levels above these values will produce an ESD condition.
Because of the notoriety surrounding ESD incidents, particularly fatal ones, when they occur, the applicants are aware of someone, as early as 2007-09, developing and installing a sensor system for detecting voltage levels which can injure or kill someone, and sound a visual and/or audio alarm to warn people near or in the water that a dangerous condition exists. The system was installed on boat docks in Central Missouri and is still in operation.
Also, as early as 1990, the United States Department of Agriculture in a handbook on Effects of Electrical Voltage/Current on Farm Animals: How To Detect and Remedy Problems addressed similar safety concerns regarding farm livestock and presented a testing apparatus for sensing dangerous voltage levels in water on farms from which animals drank or bathed. In addition, a number of U.S. patents and published applications address similar safety considerations with respect to swimming pools, large bodies of water such as lakes, as well as safety around oceanic oil drilling platforms. The patents include the following: U.S. Pat. Nos. 3,510,766; 3,784,903; 3,869,668; 5,005,007; 8,686,713; and 9,285,396. The published applications include: 2015/0198548, 2016/0154036, and 2016/0299178.
While these previous systems or devices may work well for their intended purpose, they do have drawbacks. Most importantly, as pointed out by the Electrical Shock Drowning Prevention Association (ESDPA) in their position statement of June, 2016 on “Green Light Devices”, prior art detectors create a “false sense” of security in that they are reactive devices, not predictive devices. That is, they only indicate that a dangerous condition exists, not that there is an impending danger of such a condition.
In addition, existing sensors or detectors have a limited operating range. Accordingly, a threat condition may exist which could go undetected if it exists outside the current operating range of sensors. In addition, if a system employs multiple sensors, unless the sensors are isolated from one another, it may be difficult to determine the extent of a danger zone because of overlapping areas or zones of water monitored by the sensors. Further, current sensors or detectors are prone to providing false readings. These can be caused by, for example, ground loops resulting from using the earth as an electrical conductor, plastic floats that act as a capacitor whereby a varying voltage level is produced due to wave action, noise created by boat propellers, and radio frequency (rf) interference due to radio transmission equipment found on boats or docks, faulty electric motors, etc.
In many recreational areas surrounding a lake or other body of water, it is commonplace to find a large number of individual docks used by recreational home owners and their guests; and it is also commonplace for people, particularly children to swim or wade in the water around such docks. Further found in these areas are multi-slip docks maintained by hotels, boat rental facilities, etc. Each such site represents a separate location for potential danger given the large amount of electrical equipment (lighting, audio systems, winches, etc.) located on or near these installations.
One issue for owners of these properties is insurance. A reliable shock detection system, properly installed and in compliance with local ordinances helps keep insurance premiums down for owners of these properties because such an installed system assures a safe environment for swimmers, boaters, etc.
Accordingly, there is a need for a simple, efficient shock alert warning system using reliable sensors and associated apparatus which accurately detect voltage levels approaching, reaching, or exceeding a danger threshold and which automatically alarm people in the vicinity of a danger area, as well as those having oversight of the area. Doing so can provide additional assurance the safety of those otherwise in danger as well as alerts those responsible for the site of the need to find the cause of the problem producing the dangerous condition and fixing it.